1. Field of the Invention
Embodiments of the present application relate to a differential circuit, in particular, the embodiments relate to a differential circuit usable in an optical receiver.
2. Related Background Arts
An optical receiver generally implements with a differential circuit in the front end thereof. It has been sometimes raised as a subject to be solved that, a differential circuit and a trans-impedance amplifier (hereafter denoted as “TIA”) widely used in the optical receiver often shows a gain peaking or a gain enhancement by about a few decibel (dB) in low frequencies less than 100 kHz, which is less than the cut-off frequency of the TIA. This is due to the self-heating effect of a bipolar transistor type of, what is called, the hetero-junction bipolar transistor (HBT). Such a gain enhancement or gain peak causes less quality of signals to be transmitted or received. The present invention provides solutions for compensating this gain enhancement or the gain peak.